Atmail is a fully-featured email server and Webmail client, allowing users to send and receive email via a Web browser or mobile device. It has full support for
IMAP mailboxes, and an optional email-server mode that uses EXIM as the MTA. Features include a scheduler, MySQL backend support, spell-check, address book, calendar user preferences, multiple accounts, SpamAssassin support, migration scripts from other mail servers, a customizable interface, an attractive AJAX interface, an optional group sharing Calendar/Addressbook, and an Outlook plugin to sync Contacts/Tasks/Calendar data between a Desktop, Mobile, and Webmail client or other email users.

Pico is a fast, full featured mobile application for any Java (J2ME) or Symbian cellphone. Including full HTML Web browsing, feature-rich email, multimedia-enabled SMS, and an RSS feed reader, Pico combines all the rich functionality of PicoWeb, PicoMail, PicoSMS, and PicoRSS into a single application.

QuiteSleep is an Android application that controls which people can interrupt your sleep, or any other activity defined by start and end times. In addition to muting calls, it can send an SMS and email with predefined text to advise callers that you are sleeping or busy.

Address Book Server allows you to share your
contacts and calendar events with others connected
to your network or over the Internet. Each
participant synchronizes their contacts with the
server hosted on your own system. Address Book
Server supports the full Address Book and iCal
schema. The server also provides a friendly Web
interface and an iPhone client which let you
access your contact details remotely.

The OXtender for Thunderbird is an addon for Thunderbird (and Lightning) to provide users full access to appointments and contacts stored in the Open-Xchange Server and use Thunderbird as a rich client online and offline.

HordeZpush provides ActiveSync synchronisation between smartphones, PDAs, and Horde groupware. It is based on the Zpush project and adds backends that synchronize contacts and calendars with Horde. It has been tested with Horde 3.3.5, Kronolith 2.3.2, Turba 2.3.2, and Z-Push 1.2.1.